Web guide apparatus

ABSTRACT

A web guide apparatus wherein a web passes from an entrance web guide roller over an exit web guide roller in which the exit web guide roller is mounted on an exit roller mounting base for movement relative thereto in a direction crosswise of the path of web travel to effect correction of misalignment of the web under the control of a web position detector and in which the exit roller mounting base and the entrance roller are mounted for pivotal movement relative to the path of web travel and are pivoted in unison about their respective pivot axes when the movement of the exit roller relative to the exit roller mounting base exceeds a preselected value.

United States Patent [451 Sept. 26, 1972 Bonner [54] WEB GUIDE APPARATUS [72] Inventor: William A. Bonner, Appleton, Wis.

[73] Assignee: Rockford Servo Corporation,

Rockford, ill.

[22] Filed: Aug. 25, 1971 211 App]. No.1 174,686

52 s. Cl ..226/19, 226/21 [5 1] Int. Cl. -.I..B65h 25/08 [58] Field of Search ..228/3, 19, 21, 20, 22, 23

[56] I References Cited I UNITED STATES PATENTS 3,373,288 3/1968 Otepka et al. ..226/21 x 3,390,823 7/1968 Ott ..226/19 1/1967. Jacobsen ..226/19 X Primary ExaminerAllen N. Knowles Assistant Examiner-Gene A. Church Attorney-Vernon J. Pillote 57 ABSTRACT A web guide apparatus wherein a web passes from an entrance web guide roller over an exit web guide roller in which the exit web guide roller is mounted on an exit roller mounting base for movement relative thereto in a direction crosswise of the path of web travel to effect correction of misalignment of the web under the control of a web position detector and in which the exit roller mounting base and the entrance roller are mounted for pivotal movement relative to the path of web travel andare pivoted in unison about their respective pivot axes when the movement of theexit roller relative to the exit roller mounting base exceeds a preselected value.

19 Claims, 5 Drawing Figures" WEB GUIDE APPARATUS BACKGROUND It is known to provide so-called steering type web guide apparatus in which a web guide roller is mounted for combined lengthwise shifting and lateral tilting movement about an effective center spaced a substantial distance from the roller in the direction of the entering web span. The lengthwise shifting of the roller in a direction opposite the direction of deviation of the web from the desired path tends to draw the web laterally with the roller to effect a rapid correction of the deviation of the web from the desired path. Since a traveling web in frictional engagement with a roller will tend to move at right angles to the axis of the rotating roller, the web will tend to move toward the end of the roller which is first contacted by the traveling web. However, such steering type web guide apparatus tend to stress or stretch one edge of the web more than the other and, dependent on various factors including the width of the web and web stiffness, may tend to cause wrinkling and even tearing of the web.

It is also known to provide web guide apparatus such as shown in the U.S. Patent to Robert D. Rule No. 3,581,963 utilizing two or more rollers mounted for movement in unison about an effective center or pivot axis which lies generally in the plane of the entering web span. In such apparatus, the several rollers are maintained parallel so that there is no stressing or stretching of the web between the entering and exiting rollers. Instead, the entering web span is merely twisted slightly about its lengthwise axis but is not stressed or stretched appreciably at either of its edges. However, if the web entering the web guide apparatus is subject to large lateral deviation or run-out from the desired path of travel, then the displacement type web guide apparatus must move through a substantial arc and, when the spacing between the entering and exiting rollers is large, the displacement type web guide apparatus requires very large side clearance. In addition, as the spacing between the entering and exiting rollers is increased, the problem of providing a rigid movable frame for interconnecting the rollers to maintain the same in parallelism is correspondingly aggravated.

SUMMARY OF THE INVENTION The present invention provides an improved web guiding apparatus utilizing a steering type exit web guide roller mounted on an exit roller mounting base for movement relative thereto about an instantaneous center spaced laterally from the exit web guide roller. The exit web guide roller is moved relative to its mounting base with a combined lengthwise shifting and lateral tilting movement, herein sometimes referred to as steering motion, under the control of a web position detector, in a direction to correct deviation of the web from the desired path of web travel. An entrance web guide roller is mounted for movement about a pivot axis adjacent the entrance roller and mechanism responsive to shifting of the exit roller relative to its base is provided for pivoting the entrance roller about its axis in a direction to correct deviation of the web from the desired path of web travel. The exit roller mounting base is pivotally supported for movement about an axis adjacent the exit roller and the mechanism which effects pivotal movement of the entrance roller also pivots the exit roller mounting base through an angle corresponding to the angular movement of the entrance roller. The mechanism for effecting pivotal movement of the entrance roller about its pivot axis is advantageously operative only when the shifting movement of the exit roller relative to its base exceeds a preselected value. The pivot axis of the entrance roller preferably extends in the direction of the entering web span and the pivot axis of the exit roller mounting base preferably extends in the direction of the exiting web span to minimize stressing and/or stretching of the web as it enters and exits from the web guide apparatus. Since the exiting web span undergoes substantial movement in a direction perpendicular to the plane of the exiting web span during the web guiding operation, the web position sensor is preferably located in advance of the exiting roller. The web position detector is preferably mounted on the exit roller mounting base for movement therewith so as to substantially compensate for the triangulation error which otherwise occurs when locating the web position sensing device in advance of the exiting web guide roller.

An important object of this invention is to provide a web guide apparatus utilizing a steering type exit web guide roller and which minimizes stressing or stretching of the web when the entering web undergoes large runout.

Another object of this invention is to provide an improved web guide apparatus which can accommodate a wide runout or variation in the position of the entering web without requiring a large side clearance to accommodate movement of the web guide apparatus.

Still another object of this invention is to provide a web guide apparatus having widely spaced entering and exiting web guide rollers and which does not require a rigid movable frame to interconnect the entering the exiting web guide rollers.

Still another object of this invention is to provide a web guide apparatus which can be made stable in operation even with webs running at high speeds and with large run-out in the entering span.

These, together with other objects and advantages of this invention will be better understood by reference to the following detailed description when taken in connection with the accompanying drawings wherein:

FIG. 1 is a plan view of a web guide apparatus embodying the present invention;

FIG. 2 is a side elevational view of the web guide .apparatus of FIG. 1;

FIG. 3 is a plan view of the web guide apparatus showing the parts in a moved position thereof;

FIG. 4 is a transverse sectional view through the web guide apparatus taken on the plane 44 of FIG. 2, with the exit roller operating mechanism shown diagrammatically; and

FIG. 5 is a schematic diagram illustrating the controls for the entrance roller operating mechanism.

Referring now more specifically to the accompanying drawings, the web guide apparatus of the present invention is shown applied in a web guiding system for guiding a web W intermediate its ends. The web guide apparatus in general includes an exit web guide roller assembly 10 and an entrance roller assembly 11 spaced laterally a substantial distance preferably one web width or more from the exit roller assembly. In the embodiment shown, the entrance roller assembly is spaced a relatively large distance which is many times the width of the web and an intermediate web guide roller assembly 12 is provided to engage the web span Ws intermediate the entering and exiting web guide roller assemblies to inhibit fluttering of the web in a direction transverse to the plane of the web. It is to be understood, however, that the intermediate web guide roller assembly 12 can be omitted in some applications where, by reason of low web speed or web stiffness or reduced spacing between the entrance and exiting rollers, the problem of fluttering of the web intermediate the entrance and exiting web guide rollers is not encountered.

The exit web guide roller assembly is of the steering type wherein the exiting web guide roller is supported for combined lengthwise shifting and lateral tilting movement about an instantaneous center spaced laterally from the exiting web guide roller and extending transverse to the-plane of the web span Ws as it enters the exiting web guide roller. The exit web guide roller assembly 10 is mounted on an exit roller mounting base 13 and various different mechanism, for example as shown in the U.S. Patents to Robert W. Ott, Jr. Nos. 3,390,823, and 3,583,615; the U.S. Patent to Wood, Jr. No. 2,722,415 and in the U. S. Patent to Fife No. 2,797,071, may be utilized to mount the exit web guide roller assembly on the base 13. In the embodiment illustrated, the exit roller mounting assembly is of the general type shown in U. S. Pat. No. 3,390,823. As more fully disclosed in that patent, a roller or rollers 15 are supported for axial rotation as by journals 16 secured to a support 17 that extends crosswise of the path of web travel between the journals. The support 17 is mounted as by followers 18 that slidably engage guide bars 19. The followers 18 are shown secured to the support 17 and the guide bars 19 are shown secured to the exit roller mounting base and spaced thereabove as by spacers 21 (FIGS. 2 and 4) to allow free sliding movement of the followers along the guide bars. The guide bars have a longitudinally arcuate configuration and have a common are center spaced laterally a substantial distance, preferably of the order of one web width or more from the exit roller. The guide bars have a noncircular cross section such as the square cross section shown, and the followers slidably but nonrotatably engage the guide bars to inhibit turning of the web guide roller assembly about the axis of the guide bars. In the embodiment illustrated, a single arcuate guide bar and follower is shown adjacent each end of the exit roller, it being understood the two or more radially spaced guide bars and followers are preferably provided adjacent each end of the exit roller for a more stable support, as more fully disclosed in the aforementioned U.S. Pat. No. 3,390,823.

The exit web guide roller 10 is mounted for steering movement relative to the exit roller mounting base 13 and a web position sensing and control means 22, described more fully hereinafter, is provided for sensing the lateral position of the web and for moving the exit web guide roller in a steering motion relative to the base 13 in a direction to correct deviation of the web from the desired path of web travel. The instantaneous center of movement designated Ec of the exit steering roller extends transverse to a plane through the web span Ws as it enters the exit roller and, in undergoing steering movement, the exit web guide roller tends to stress one edge or the other of the web depending upon its position relative to the desired path of web travel. The stressing of the web edges increases as the amplitude of the steering movement is increased. In accordance with the present invention, the entrance web guide roller assembly 1 l is also shifted in a direction to correct deviation of the web from its desired path of travel and to reduce stressing and stretching of the web span Ws.

The entrance web guide roller assembly 11 includes a roller 24 mounted for axial rotation as by journals or bearing blocks 25 adjacent opposite ends of the entrance roller and the bearing blocks are supported as by brackets 26 on a movable support 27 that extends crosswise of the path of web travel to interconnect the bearing blocks. The entrance web guide roller assembly is supported for pivotal movement about an axis transverse to the roller axis. In the preferred embodiment shown, the pivot axis of the entrance web guide roller assembly designated P1 is located approximately medially between the ends of the entrance web guide roller 24 and a pivot pin 28 (FIG. 2) is provided atthat location to pivotally mount the movable support 27 on a bracket 29 attached to fixed entrance roller mounting base 31. Outboard supports, conveniently in the form of arcuate guide bars 32 and followers 33 are preferably provided between the movable support 27 and the base 31 to stabilize the entrance roller and, as shown in FIG. 1, the arcuate guide bars are formed concentric with the pivot P1. It will be understood that a physical pivot pin is not essential at the location P1 and that the arcuate guide bars or other means can be utilized to form a virtual pivot for the entrance web guide roller.

A control apparatus 35 described more fully hereinafter, is provided for effecting pivotal movement of the entrance web guide roller assembly about its pivot axis P1 in a direction to aid in correcting deviation of the web from the desired path of web travel. The angular movement of the entrance web guide roller assembly 11 about its pivot axis P1 is also utilized to change the angular position of the exit web guide roller 15 and, for this purpose, the exit web guide roller mounting base 13 is mounted for pivotal movement about an axis P2 which generally parallels the pivot axis P1 of the entrance web guide roller. As best shown in FIGS. 1 and 2, the exit roller mounting base 13 is pivotally supported as by a pivot pin 38 on a stationary base 39. The pivot axis P2 extends transverse to the axis of the exit web guide roller 15 and is preferably located approximately medially between the ends thereof. Outboard supports such as arcuate guide bars 41 and followers 42 are attached to the stationary support 39 and to the exit roller mounting base 13 to stabilize the latter during pivotal movement about the axis P2. As shown in FIG. 1, the arcuate guide bars 41 have a common arc center at P2. While a pivot pin 38 is herein shown provided for pivotally securing the exit roller mounting base 13, it will be apparent that other means such as the arcuate guide bar and follower arrangement described can be utilized to form a virtual pivot for the exit roller mounting base.

In the embodiment shown, the entrance and exit web guide roller assemblies and Ill are spaced apart a substantial distance and an intermediate web guide roller assembly 12 is provided to minimize fluttering of the web as it passes from the entrance to the exit web guide roller. The intermediate web guide roller assembly is also mounted for pivotal movement about an axis P3 generally paralleling the pivot axes P1 and P2 and extending transverse to the intermediate roller intermediate the ends thereof. In general, the intermediate web guide roller assembly includes a roller 44 supported for axial rotation on bearing blocks 45 attached to a movable support 46 that extends crosswise of the path of web travel to interconnect the bearing blocks. The movable support 46 is pivotally mounted as by a pivot pin assembly 47 on a stationary base 48 and I outboard supports, conveniently in the form of arcuate guide bars 49 and followers 50 are provided to stabilize the intermediate web guide roller assembly during pivotal movement about the pivot axis P3. As shown, the arcuate guide bars 49 have a common are center at the pivot axis P3. I

The entrance web guide roller support 27, the exit roller mounting base 13 and the intermediate roller support 46 are interconnected for simultaneous substantially equal angular movement about their respective pivot axes P1, P2 and P3. As shown in FIGS. 1, 2 and 3 this is conveniently effected by links 51 and 52. Link 51 is pivotally connected respectively at 5111 and 51b to the entrance roller support 27 and to the intermediate roller support 46 and link 52 is pivotally connected respectively at 52a and 52b to the intermediate roller support 46 and to the exit roller mounting base 13, with the pivots 51a, 51b and 52a, 52b being spaced substantially equal radial distances from the respective pivot axes P1, P2, and P3 to at least substantially equalize angular movement of the entrance roller, the intermediate roller and the exit roller mounting base.

In order to minimize stressing of the web, the web guide apparatus is arranged in a web guiding system so that the pivot axes PI and P2 of the entrance web guide roller and the exit roller mounting base respectively extend generally parallel to the planes of the entering web span designated We and the exiting web span designated Wx. The web W can enter the web guide apparatus from a web unwind roll, or a previous web processing apparatus, the final roller of which prior web processing apparatus or web unwind roll apparatus is diagrammatically shown at 55. Roll 55 is supported for axial rotation but is not movable and the entrance web guide roller 11 is positioned so that the entering web span We generally parallels the pivot axis P1 so that the entering web span is merely twisted about its lengthwise axis without significant stretching of the web edges. Similarly, the exiting web Wx can pass to a subsequent web processing apparatus or to a web rewind apparatus, the initial roll of which subsequent apparatus is diagrammatically indicated at 56. Roll 56 is supported for axial rotation but is otherwise non-movable and the exit web guide roller is positioned with respect to roll 56 so that the exiting web span Wx extends generally parallel to the pivot axis P2. With this arrangement, the exiting web span is also merely twisted about its lengthwise axis without significant stretching of the web edges in response to pivotal and steering movement of the exit web guide roller. As is well understood in the art, exact parallelism between the entering web We and the pivot P1 or the exiting spans We and Wx during pivotal movement of the rollers.

The exit web guide roller assembly 10, the entrance web guide roller assembly 1 l, and the intermediate web guide roller assembly 12 are conveniently mounted on a common frame herein shownv in the form of spaced beams 61 which extend lengthwise of the path of web travel, adjacent opposite sides thereof. The web span Ws extending from the entrance web guide roller 11 to the exit web guide'roller 10 extends generally parallel to the plane of motion of the entrance and exit'web guide rollers and the intermediate web guide roller is positioned to engage the web span Ws at a location slightly offset from a plane through the point of tangency of the web span Ws with the entering and exiting web guide roller so as to inhibit fluttering of the web span Ws. As shown, the web span Ws passes over the entrance roller 11, under the intermediate roller 12 and over the exit web guide roller 10. The pivot axes P1, P2 and P3 extend generally'perpendicular to the web span Ws and the instantaneous center E0 of the exit web guide roller also preferably extends generally perpendicular to the web span Ws at a location spaced in advance of the exiting web guide roller a substantial distance, for example one or more web widths.

The web edge sensing and control apparatus 22 for moving the exit web guide roller relative to the base 13 can be of various different known types which operate to sense the lateral position of the web relative to the desired path of web travel and to move the exit web guide roller 10 relative to its support base 13 in a direction and amount proportional to the deviation of the web from the desired path of travel. The web edge sensing and control apparatus may, for example, use pneumatic, photoelectric or mechanical means for sensing the lateral position of the web and pneumatic, hydraulic or electric mechanism or a combination thereof for moving the web guide roller. In the form diagrammatically illustrated in FIG. 4, a pneumatichydraulic web position sensing and control system is shown, which control system is more fully disclosed in the aforementioned U. S. Pat. No. 3,407,706, the disclosure of which is incorporated herein by reference. In general, the apparatus 22 includes a web position sensor 71, diagrammatically shown in FIG. 4 as of the pneumatic type, and having a transmitting orifice 71a disposed at one side of the web and a receiving orifice 71b located at the other side of the web. In general, the transmitting orifice 71a transmits a stream of air toward the receiving orifice 71b and the web edge variably interrupts the stream of air" to vary the pressure at the sensing orifice 71b correlative with the position of the web edge. The control apparatus also includes a pressure responsive device 75 which, as diagrammatically shown in FIG. 4, comprises a diaphragm 76 clamped between diaphragm housing members 77 and 78 and sealed thereto as by seal rings 79. The diaphragm housing members define chambers 81 and 82 at opposite sides of the diaphragm. An air supply is provided and, as diagrammatically shown in FIG. 4, air pressure is supplied by a constant pressure supply preferably in the form of a centrifugal air pump 83 driven by a motor 84 through a shaft 85. As disclosed in the aforementioned patent, the centrifugal air pump will produce an outlet pressure which is substantially constant and having a magnitude dependent upon the size of the centrifugal air pump and the speed of operation. The air pump outlet is connected through a .conduit 86 and through a line 87 leading to the transmitting orifice 71a in the sensor 71. The sensing orifice 71b is connected through a line 89 to the pressure chamber 81 and the other pressure chamber 82 is vented to atmosphere through a vent 770. In order to prevent ingestion of foreign material into the sensing orifice, air under a relatively lower pressure than that supplied to the transmitting orifice is supplied to the sensing orifice 71b to, maintain a slight outflow of air. For this purpose, the air pump discharge line 86 is connected through a conduit 93 and flow restrictor 94 to the pressure chamber 81. The size of the flow restrictor 94 is selected so that the pressure supplied to the sensing orifice is substantially lower than the pressure supplied to the transmitting orifice and just sufficient to maintain a slight outflow of air through the sensing orifice. The control apparatus which is operated by the pressure responsive device 75 may be of any conventional construction. In the embodiment illustrated, the control apparatus comprises an hydraulic four-way reversing valve including a valve casing 101 having an inlet chamber 102, first and second control chambers 103 and 104, and first and second outlet chambers 105 and 106 adjacent opposite ends'of the casing. Fluid under pressure is supplied to the inlet chamber 72 from an hydraulic pump 108 conveniently driven by motor 84 through a drive train 109. The pump 108 has its inlet line 108a connected to a reservoir 110 for hydraulic fluid and its outlet line 108!) connected through a relief valve 111 and filter 112 to the valve inlet chamber 102. A valve member 115 is connected to the diaphragm 76 to reversibly control the flow of hydraulic fluid to control chambers 103 and 104 and the valve has spaced valve elements operative in the neutral position to close off communication between the control chambers and both inlet and outlet chambers. As the valve element moves upwardly, it allows the inlet chamber 102 to communicate with the control chamber 103 and simul taneously communicates the control chamber 104 with the outlet chamber 106. Conversely, when the valve moves downwardly from the position shown, it communicates the control chamber 104 with the inlet chamber 102 and communicates the control chamber 103 with the outlet 105.Fluid under pressure is thus reversibly supplied to the control chambers 103 and 104 and these chambers are connected through hydraulic lines 117 and 118, to the exit roller operating mechanism, herein shown in the form of a double-acting hydraulic cylinder and piston assembly 120, 121. As shown, the cylinder 120 is swivelly connected at 120a to the mounting base 13 and the piston is swivelly connected at 121a to the exit roller support 17, so as to effect shifting movement of the exit web guide roller relative to the mounting base 13, in response to extension and retraction of the piston. Valve is urged by a spring 1 16 in a direction opposite the direction of movement of the valve member by pressure in chamber 81 acting on the diaphragm 76 and the spring pressure is adjusted by a screw 117 so that the valve member will be in its centered position shown in FIG. 4 when the web edge partially interrupts the air stream from transmitting ori- The exiting web span Wx will undergo substantial movement in a direction normal to the plane of the exiting span during the web guiding operation. In order to avoid the problems incident to sensing the position of a web at a location where the web is subject to wide passline variation or fluctuation, the web position sensing device 71 is herein shown positioned to sense the web at a location in advance of the exiting web guide roller where the web does not undergo a wide pass-line fluctuation. However, as more fully disclosed in the U. S. Patent to Robert D. Rule No. 3,581,963, a triangulation error as described in that patent occurs when the web edge is sensed at a location in advance of the plane of the exiting web. In order to minimize the triangulation error due to sensing of the web edge at a location in advance of the exiting web guide roller, the web posi tion sensing device 71 is mounted on the pivotal exit roller mounting base 13 for movement therewith. As shown, a support rod 131 is mounted by brackets 132 on the exit roller mounting base 13 to extend crosswise of the path of web travel and the web position detector 71 is mounted by a bracket 133 and follower 134 for adjustment along the rod 131. The follower can be locked in adjusted position along the rod in accordance with the width of the web being guided and, when the exit roller mounting base pivots about its axis P2, the web position sensor 71 has a component of movement in a direction crosswise of the path of web travel, and which substantially compensates for the triangulation error caused by the spacing of the web sensor 71 in advance of the exiting web guide roller.

It is contemplated that the exit web guide roller 10 be moved in a steering motion relative to the base 13 to correct for small deviation from the desired path of web travel and that the entrance roller be used to aid in correcting larger deviations of the web from the desired path. Accordingly, the entrance roller operating mechanism 35 is arranged to effect pivotal movement of the entrance roller when the movement of the exit roller relative to its mounting base exceeds a preselected value. As diagrammatically shown, a means conveniently in the form of a rod 141 is connected as by a pivot pin 142 to the exit roller support 17 and is guidably supported as at 143 in a support swivelly mounted on the exit roller mounting base 13 at a location such that the rod extends generally tangent to the path of movement of the exit web guide roller relative to the base 13. Various different conventional operating means can be utilized to effect pivotal movement of the entrance roller under the control of the sensing rod 141 and, in the embodiment shown, a reversible electric motor 145 is provided for reversibly driving a screw 146 and follower 147. In the form shown, the follower is connected to the intermediate support base 46 which is, in turn, connected through link 51 to the movable entrance roller support 27 and through link 52 with the exit roller mounting base 13. It is understood, however, that the operating mechanism 35 could be connected to any of the aforementioned items. Since the base 46 undergoes movement about the center P3, the connection of the motor 145, screw 146 and follower 147 must be such as to accommodate the limited angular movement. For example, the connection between the motor and screw can employ a universal joint (not shown) for driving the screw and the connection between the screw and follower can have a swivel joint.

The reversible electric motor 145 is reversibly operated under the control of a switch 151 mounted on the exit roller mounting base 13 and operated by cams 152a and 15% on the exit roller position sensing rod 141. As diagrammatically shown in FIG. 5, switch 151 can be of the three-way type which is normally positioned in a center or neutral position as shown in FIG. and which is movable under the control of cams 152a and 152!) into engagement with contacts 151a and l51b respectively. Reversible motor 145 has motor windings 145a and 145b and a relay mechanism is provided for-reversibly controlling the power supplied to at least one of the windings to reversibly actuate the motor-under the control of switch 151. As diagrammatically illustrated in FIG. 5, power is supplied from power supply conductors 156 and 157 adapted for connection to a suitable electrical power supply. Switch 151 is connected to one of the conductors 156 and contact 151a is connected through a normally closed relay contact 155a and relay 154 to the other power conductor 157. Similarly, contact 151b is connected through a normally closed relay contact 1540 and relay 155 to the conductor 157. Power from the conductor 156 is supplied through normally opened relay contacts 154b and 'l55b through conductor 158 to the winding 145b, which winding is otherwise connected through a phase shifting capacitor 160 to the other power conductor 157. Power is reversibly supplied to the other winding 145a under the control of normally opened relay switches 1550, 154e, 1544 and 155d. Relay 154 is operative, when energized, to open normally closed contact 154a and close normally opened contacts 154b, 1540 and 154d. Similarly, relay 155 is operative when energized to open normally closed contact 1550 and close normally opened contacts 155b, 155c and 155d. Thus, when the switch 151 is moved to establish a circuit to relay 154, the latter is energized and opens the contacts 154a leading to relay 155 and simultaneously closes the contacts l54b to apply power to winding '145b and to also close contacts 1540 and 154d to apply power in one direction to winding 145a. Conversely, when switch 151 is moved to establish a circuit through contact 151b, relay 155 is energized to open contact 155a and also close normally opened contact 15512 to again establish a circuit through winding 145b.

However, closing of contacts 155:: and 155d applies.

power through winding 145a in the reverse direction from that previously described so as to reverse the direction of rotation of the motor 145.

OPERATION From the foregoing it is thought that the construction and operation of the web guide apparatus will be readily understood. The entrance web guide roller 11 is mounted for movement about a pivot axis Pl from a normal position extending perpendicular to the desired path of web travel and the intermediate web guide roller 12 and the exit roller mounting base 17 are similarly pivotal about their respective pivot axis P3 and P2 from a normal position shown in FIG. I extending perpendicular to the desired path of web travel indicated by the arrows A in FIG. 1. In addition, the exit web guide roller 10 is supported for combined lengthwise shifting and lateral tilting movement relative to the exit roller mounting base from a centered position about an effective center Ec which is transverse to the plane of the web span Ws extending between the entrance and exit rollers. When the exit roller mounting base 13 is in its normal position shown in FIG. 1, the exit roller 10 will extend perpendicular to the desired path of web travel when the exit roller is in its centered position shown in FIG. 1 with respect to the exit roller mounting base. Thus, when the web span Ws is following the desired path of web travel shown in FIG. 1, the entrance and intermediate web guide rollers are in their normal position and perpendicular to the desired path of web travel and the exit roller will be in its centered position relative to base 13 and will also be perpendicular to the desired path of web travel.

The web position sensor 71 senses deviations of the web from the desired path of web travel and reversibly operates the exit web guide roller to move the same relative to the exit roller mounting base 13 in a direction to correct deviation of the web from the desired path of web travel. In general, the web sensing and control apparatus operates to shift the exit web guide roller lengthwise in a direction opposite the direction of deviation of the web from the desired path of web travel and also simultaneously tilts the exit web guide roller laterally in a direction to apply a continuing correction to the web. When the movement of the exit web guide roller assembly from its centered position relative to the base 13 exceeds a preselected value, for example one inch in either direction from its centered position, the cams 152a and 1521; operate switch 151 to drive the entrance roller operating mechanism in a direction to tilt the entrance roller in a direction to correct deviation of the web from the desired path of web travel. In general, the entrance roller is pivoted in the same direction as the tilting movement of the exit web guide roller relative to the exit roller mounting base. Because of the large space between the entrance and exit roller, a small pivotal movement of the entrance roller will produce a relatively large correction of the path of web travel and the angular motion of the entrance roller is transmitted to the exit roller mounting base 13 so as to pivot the latter in the same direction and through approximately the same angle. This effectively increases the angle of tilt of the exit web guide roller relative to the path of web travel and, as the path of web travel becomes corrected, the web edge sensor and control mechanism 22 operates to move the exit web guide roller back to its centered position with respect to the exit roller mounting base.

It is preferred that the exit web guide roller assembly and the operating mechanism 22 for moving the same relative to the mounting base have a relatively high speed of response as compared to the entrance roller operating mechanism so that the steering motion of the exit roller relative to its mounting base 13 operates to correct small deviations of the web from the desired path of web travel without causing cycling or hunting of the entrance web guide roller operating mechanism. However, if the run-out of the web is large, the entrance roller operating mechanism operates to pivot the entrance roller and the exit roller mounting base about their respective pivot axes to correct large deviations in the path of web travel.

In the embodiment illustrated, a single speed reversing motor 145 is shown with a single" doublethrow switch 151 for controlling operation of the same. it is contemplated that, for high speed operations, or where there is very rapid run-out of the entering web, that the motor 145 could be a multiple speed motor and that additional limit switches could be provided for operation in response to movement of the exit web guide roller relative to its base in excess of the value sensed by cams 152a and 152b, to provide higher speed operation of the entrance web guide roller operating mechanism under these conditions.

Since the entrance web guide roller is pivoted to aid in correcting the path of web travel when the exit web guide roller is moved a preselected minimum distance form its centered position, the exit web guide. roller does not have to be mounted for or moved through a large distance in order to effect web correction. This minimizes the lateral clearance required for the web guide apparatus. Moreover, a rigid movable frame structure is not required to interconnect. the entrance and exitweb guide roller. As shown in FIGS. 1 and 3, the entrance roller is made long as compared to the width of the web and sufficient to accommodate the full run-out of the incoming web. The exit roller, however, can be relatively shorter than the entrance roller since the entrance roller is pivoted about axis P1, to correct large run-out of the incoming web.

While a preferred embodiment of the present invention has been herein illustrated and described, it will be understood by those skilled in the art that the invention is not so limited and that it may be otherwise embodied within the scope of the following claims.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. An apparatus for guiding a moving web along a preselected path of web travel comprising, an entrance web guide roller, entrance roller mounting means supporting said entrance roller for axial rotation and mounting the entrance web guide roller for pivotal movement in a plane of motion generally paralleling the axis of the entrance roller about a first pivot axis adjacent said entrance roller, an exit web guide roller spacedin a direction lengthwise of the path of web travel from the entrance roller, an exit roller mounting base mounted for pivotal movement in a plane of motion generally paralleling the plane of motion of the entrance roller about a second pivot axis adjacent the exit roller, exit roller mounting means supporting said exit roller for axial rotation and mounting said exit roller on said exit roller mounting base for combined endwise shifting and lateral tilting movement relative thereto about an instantaneous center transverse to the plane of motion of the exit roller mounting base and spaced from the exit guide roller in a direction toward -'the ena trance roller, and operating means includingweb posi tion sensing means for effecting endwise shifting and tilting movement of said exit roller relative to said exit roller mounting base and for effecting pivotal movement of said entrance roller and said exit roller mounting base about their respective first and second pivot axes in a direction to maintain the web in the preselected path of web travel.

2. An apparatus for guiding a moving web in accordance with claim 1 wherein said operating means includes means responsive to the web position sensing means for effecting endwise shifting and tilting movement of said exit roller relative to said exit roller mounting base in a direction to correct deviation of the web from the preselected path of web travel, and means operative when the endwise shifting and lateral tilting movement of the exit roller relative to the exit roller mounting base exceeds a preselected value for effecting pivotal movement of said entrance roller and said exit roller mounting base in a direction to correct deviation of the web from the preselected path of web travel.

3. An apparatus for guiding webs in accordance with claim 2 wherein said last-mentioned means includes means operatively connecting said entrance roller mounting means and said exit roller mounting base to substantially equalize pivotal movement of said entrance roller and said exit roller mounting base about their respective first and second pivot axes.

4. An apparatus for guiding webs in accordance with claim 1 wherein said operating means includes a first power means responsive to the web position sensing means for effecting endwise shifting and tilting movement of the exit roller relative to said exit roller mounting base in a direction to correct deviation of the web from the preselected path of web travel, a second sensing means for sensing movement of. said exit roller relative to said exit roller mounting base, and a second power means responsive to said second sensing means for effecting pivotal movement of said entrance roller mounting means and said exit roller mounting base respectively about said first and second pivot axes in a direction to correct deviation of the web from the preselected path of web travel.

5. An apparatus for guiding webs in accordance with claim 4 wherein said second sensing means is arranged to operate said second power means only after the exit roller has moved a preselected distance relative to said exit roller mounting base.

6. An apparatus for guiding webs according to claim 5 wherein said second power means includes means interconnecting said entrance roller mounting means and said exit roller mounting base to effect substantially equal pivotal movement thereof about said first and second pivot axes.

7. An apparatus for guiding webs, according to claim 5 wherein said web position sensing means is arranged to sense the position of the web. at a location in advance of said exit web guide roller, and means mounting said web position sensing means, on said exit roller mounting base for movement therewith.

8. An apparatus for guiding webs according to claim 1 including an intermediate web guide roller located intermediate the entrance and exit web guide rollers, and intermediate roller mounting means supporting the intermediate roller for axial rotation and mounted for pivotal movement about a third axis adjacent said intermediate roller and generally paralleling said first axis.

9. A web guide apparatus according to claim 1 wherein said first and second pivot axes are located approximately midway of the ends of said entrance and exit web guide rollers respectively.

10. An apparatus for guiding a moving web along a preselected path of web travel comprising, an entrance webguide roller, entrance roller mounting means supporting said entrance roller for axial rotation and mounted for pivotal movement in a plane of motion generally paralleling the axis of the entrance roller about a first pivot axis adjacent said entrance roller, an exit web guide roller spaced in a direction lengthwise of the path of web travel from the entrance roller, exit roller mounting means supporting said exit web guide roller for axial rotation andmounting said exit web guide roller for combined endwise shifting and lateral tilting movement about an instantaneous center transverse to the plane of motion of the entrance web guide roller and spaced from the exit web guide roller in a direction toward the entrance web guide roller, web position sensing means for sensing the position of the web relative to said preselected path of web travel, operating means responsive to said web position sensing means for effecting endwise shifting and lateral tilting of said exit web guide roller in a direction to correct deviation of the web from the preselected path of web travel, and means operative when the endwise shifting and lateral tilting movement of the exit web guide roller exceeds a preselected amount for effecting pivotal movement of the entrance web guide roller about said first pivot axis in a direction to correct deviation-of the web from the desired path of web travel.

11. An apparatus for guiding a moving web according to claim wherein said last-mentioned means includes a reversible power operated means for effecting pivotal movement of said entrance web guide roller about said first pivot axis, means for sensing endwise shifting and lateral tilting movement of said exit web guide roller about said instantaneous center, and lostmotion means operation when the endwise shifting and lateral tilting of the exit roller exceeds a preselected value for reversibly operating said power operated means in a direction to correct deviation of the web from the desired path of web travel.

12. In a web guide system including an entrance web guide roller and an exit web guide roller and wherein a moving web enters the entrance web guide roller and exits from exit web guide roller in entering and exiting spans which respectively extend transverse to a plane through the entrance and exit web guide rollers, the improvement comprising entrance roller mounting means supporting said entrance roller for axial rotation and mounting said entrance roller for pivotal movement about a first pivot axis transverse to the axis of rotation of the entrance roller and extending generally in the direction of the entering web span, an exit roller mounting base mounted for pivotal movement about a second pivot axis transverse to the axis of rotation of the exit roller and extending generally in the direction of the exiting web span, said entrance roller being movable about said first pivot axis from a normal position generally perpendicular to a plane through said first and second pivot axes, means interconnecting said entrance roller mounting means and said exit roller mounting base to effect substantially equal angular movement thereof about the respective first and second pivot axes, exit roller mounting means mounting the exit roller on said exit roller mounting base for combined endwise shifting and lateral tilting movement relative to said base from a centered position about an instantaneous center transverse to a plane through the axes of the entrance and exit web guide rollers and spaced from the exit web guide roller in a direction toward the entrance web guide roller, said exit web guide roller in said centered position thereof extending generally perpendicular to a plane through said first and second pivot axes when said entrance web guide roller is in its normal position,'web position sensing means for sensing the position of the web, power operated means responsive to said web position sensing means for reversibly moving said exit web guide roller relative to said exit rollermounting base from said centered position thereof in a direction to correct deviation of the web from the desired path of web travel, and entrance roller operating means for pivoting said entrance web guide roller from said normal position thereof in a direction to correct deviation of the web from said preselected path of web travel.

13. A web guide system according to claim 12 wherein said entrance roller operating means includes means responsive to movement of said exit roller relative to said exit roller mounting base for effecting pivotal movement of said entrance guide roller about said first pivot axis.

14. A web guide apparatus according to claim 16 wherein said web position sensing means is positioned to sense the web at a location in advance of said exit web guide roller and said web position sensing means is mounted on said exit roller mounting base.

15. A web guide system according to claim 12 wherein said entrance roller operating means includes means for sensing movement of said exit roller relative to said exit roller mounting base, and means controlled by said last-mentioned means for effecting pivotal movement of said entrance roller about said first pivot axis when the movement of said exit roller from its centered position exceeds a preselected value.

16. A web guide system according to claim 12 wherein said entrance roller operating means includes a second power operated means operatively connected to said entrance roller mounting means for reversibly moving the same about said first pivot axis from said normal position thereof, a second sensing means for sensing movement of the exit roller relative to said exit roller mounting base, and means operative when the movement of the exit roller from its centered position exceeds a preselected value for actuating said second power operated means to tilt the entrance roller in a to said exit roller mounting base, and means controlled by said last-mentioned sensing means for effecting pivotal movement of said entrance roller about said first pivot axis.

19. A web guide apparatus according to claim 16 including an intermediate web guide roller, means mounting said intermediate roller for pivotal move- 

1. An apparatus for guiding a moving web along a preselected path of web travel comprising, an entrance web guide roller, entrance roller mounting means supporting said entrance roller for axial rotation and mounting the entrance web guide roller for pivotal movement in a plane of motion generally paralleling the axis of the entrance roller about a first pivot axis adjacent said entrance roller, an exit web guide roller spaced in a direction lengthwise of the path of web travel from the entrance roller, an exit roller mounting base mounted for pivotal movement in a plane of motion generally paralleling the plane of motion of the entrance roller about a second pivot axis adjacent the exit roller, exit roller mounting means supporting said exit roller for axial rotation and mounting said exit roller on said exit roller mounting base for combined endwise shifting and lateral tilting movement relative thereto about an instantaneous center transverse to the plane of motion of the exit roller mounting base and spaced from the exit guide roller in a direction toward the entrance roller, and operating means including web position sensing means for effecting endwise shifting and tilting movement of said exit roller relative to said exit roller mounting base and for effecting pivotal movement of said entrance roller and said exit roller mounting base about their respective first and second pivot axes in a direction to maintain the web in the preselected path of web travel.
 2. An apparatus for guiding a moving web in accordance with claim 1 wherein said operating means includes means responsive to the web position sensing means for effecting endwise shifting and tilting movement of said exit roller relative to said exit roller mounting base in a direction to correct deviation of the web from the preselected path of web travel, and means operative when the endwise shifting and lateral tilting movement of the exit roller relaTive to the exit roller mounting base exceeds a preselected value for effecting pivotal movement of said entrance roller and said exit roller mounting base in a direction to correct deviation of the web from the preselected path of web travel.
 3. An apparatus for guiding webs in accordance with claim 2 wherein said last-mentioned means includes means operatively connecting said entrance roller mounting means and said exit roller mounting base to substantially equalize pivotal movement of said entrance roller and said exit roller mounting base about their respective first and second pivot axes.
 4. An apparatus for guiding webs in accordance with claim 1 wherein said operating means includes a first power means responsive to the web position sensing means for effecting endwise shifting and tilting movement of the exit roller relative to said exit roller mounting base in a direction to correct deviation of the web from the preselected path of web travel, a second sensing means for sensing movement of said exit roller relative to said exit roller mounting base, and a second power means responsive to said second sensing means for effecting pivotal movement of said entrance roller mounting means and said exit roller mounting base respectively about said first and second pivot axes in a direction to correct deviation of the web from the preselected path of web travel.
 5. An apparatus for guiding webs in accordance with claim 4 wherein said second sensing means is arranged to operate said second power means only after the exit roller has moved a preselected distance relative to said exit roller mounting base.
 6. An apparatus for guiding webs according to claim 5 wherein said second power means includes means interconnecting said entrance roller mounting means and said exit roller mounting base to effect substantially equal pivotal movement thereof about said first and second pivot axes.
 7. An apparatus for guiding webs according to claim 5 wherein said web position sensing means is arranged to sense the position of the web at a location in advance of said exit web guide roller, and means mounting said web position sensing means on said exit roller mounting base for movement therewith.
 8. An apparatus for guiding webs according to claim 1 including an intermediate web guide roller located intermediate the entrance and exit web guide rollers, and intermediate roller mounting means supporting the intermediate roller for axial rotation and mounted for pivotal movement about a third axis adjacent said intermediate roller and generally paralleling said first axis.
 9. A web guide apparatus according to claim 1 wherein said first and second pivot axes are located approximately midway of the ends of said entrance and exit web guide rollers respectively.
 10. An apparatus for guiding a moving web along a preselected path of web travel comprising, an entrance web guide roller, entrance roller mounting means supporting said entrance roller for axial rotation and mounted for pivotal movement in a plane of motion generally paralleling the axis of the entrance roller about a first pivot axis adjacent said entrance roller, an exit web guide roller spaced in a direction lengthwise of the path of web travel from the entrance roller, exit roller mounting means supporting said exit web guide roller for axial rotation and mounting said exit web guide roller for combined endwise shifting and lateral tilting movement about an instantaneous center transverse to the plane of motion of the entrance web guide roller and spaced from the exit web guide roller in a direction toward the entrance web guide roller, web position sensing means for sensing the position of the web relative to said preselected path of web travel, operating means responsive to said web position sensing means for effecting endwise shifting and lateral tilting of said exit web guide roller in a direction to correct deviation of the web from the preselected path of web travel, and means operative when the endwise shifting anD lateral tilting movement of the exit web guide roller exceeds a preselected amount for effecting pivotal movement of the entrance web guide roller about said first pivot axis in a direction to correct deviation of the web from the desired path of web travel.
 11. An apparatus for guiding a moving web according to claim 10 wherein said last-mentioned means includes a reversible power operated means for effecting pivotal movement of said entrance web guide roller about said first pivot axis, means for sensing endwise shifting and lateral tilting movement of said exit web guide roller about said instantaneous center, and lost-motion means operation when the endwise shifting and lateral tilting of the exit roller exceeds a preselected value for reversibly operating said power operated means in a direction to correct deviation of the web from the desired path of web travel.
 12. In a web guide system including an entrance web guide roller and an exit web guide roller and wherein a moving web enters the entrance web guide roller and exits from exit web guide roller in entering and exiting spans which respectively extend transverse to a plane through the entrance and exit web guide rollers, the improvement comprising entrance roller mounting means supporting said entrance roller for axial rotation and mounting said entrance roller for pivotal movement about a first pivot axis transverse to the axis of rotation of the entrance roller and extending generally in the direction of the entering web span, an exit roller mounting base mounted for pivotal movement about a second pivot axis transverse to the axis of rotation of the exit roller and extending generally in the direction of the exiting web span, said entrance roller being movable about said first pivot axis from a normal position generally perpendicular to a plane through said first and second pivot axes, means interconnecting said entrance roller mounting means and said exit roller mounting base to effect substantially equal angular movement thereof about the respective first and second pivot axes, exit roller mounting means mounting the exit roller on said exit roller mounting base for combined endwise shifting and lateral tilting movement relative to said base from a centered position about an instantaneous center transverse to a plane through the axes of the entrance and exit web guide rollers and spaced from the exit web guide roller in a direction toward the entrance web guide roller, said exit web guide roller in said centered position thereof extending generally perpendicular to a plane through said first and second pivot axes when said entrance web guide roller is in its normal position, web position sensing means for sensing the position of the web, power operated means responsive to said web position sensing means for reversibly moving said exit web guide roller relative to said exit roller mounting base from said centered position thereof in a direction to correct deviation of the web from the desired path of web travel, and entrance roller operating means for pivoting said entrance web guide roller from said normal position thereof in a direction to correct deviation of the web from said preselected path of web travel.
 13. A web guide system according to claim 12 wherein said entrance roller operating means includes means responsive to movement of said exit roller relative to said exit roller mounting base for effecting pivotal movement of said entrance guide roller about said first pivot axis.
 14. A web guide apparatus according to claim 16 wherein said web position sensing means is positioned to sense the web at a location in advance of said exit web guide roller and said web position sensing means is mounted on said exit roller mounting base.
 15. A web guide system according to claim 12 wherein said entrance roller operating means includes means for sensing movement of said exit roller relative to said exit roller mounting base, and means controlled by said last-mentioned means for effecting pivotal movemEnt of said entrance roller about said first pivot axis when the movement of said exit roller from its centered position exceeds a preselected value.
 16. A web guide system according to claim 12 wherein said entrance roller operating means includes a second power operated means operatively connected to said entrance roller mounting means for reversibly moving the same about said first pivot axis from said normal position thereof, a second sensing means for sensing movement of the exit roller relative to said exit roller mounting base, and means operative when the movement of the exit roller from its centered position exceeds a preselected value for actuating said second power operated means to tilt the entrance roller in a direction to correct deviation of the web from said preselected path of web travel.
 17. A web guide apparatus according to claim 16 wherein said first and second pivot axes are located approximately medially between the ends of said entrance and exit web guide rollers.
 18. A web guide system according to claim 12 wherein said entrance roller operating means includes means for sensing movement of said exit roller relative to said exit roller mounting base, and means controlled by said last-mentioned sensing means for effecting pivotal movement of said entrance roller about said first pivot axis.
 19. A web guide apparatus according to claim 16 including an intermediate web guide roller, means mounting said intermediate roller for pivotal movement about a third axis generally paralleling said first and second axes and at a location to engage the web intermediate said entrance and exit web guide rollers, and means for moving said intermediate web guide roller about a third axis to maintain the same generally parallel to said entrance roller. 